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e e been in use a number of years and are thus familiar to potential Corps users. Some pro. grams have been slightly modified to interface with data being generated from the data bank rather than in their usual formats. In a few instances basic modifications were made to the programs to permit or encourage a more systematic analysis process (than tradi- tional) to take advantage of the opportunities offered by ready access to a comprehen. sive data bank. HEC-2 (The Hydrologic Engineering Center. 1976) has served the Corps many years in performing river hydraulic analysis and is used in its traditional form. HEC-l (The Hydrologic Engineering Center, 1976) serves the double duty of general hydrologic simulation to forecast the hydrologic effects of development proposals and also integration of the hydrologic with economic damage data to provide the assessment of the expected value of annual damages (average annual damages) resulting from develop. ment alternatives. The RIA program operates by direct link to the data bank and per. forms coincident, attractiveness and vulnerability analysis, and general grid mapping. The program is adapted from work by Harvard (Honey Hill, IRW Report 71-9), and makes use of a modified version of the general grid plot program GRID. STORM and WQRRS (The Hydrologic Engineering Center, 1976) are recently developed Hydrologic Engineer. ing Center computer programs that forecast urban storm water quality and dynamic in- stream water quality response to waste loadings from treatment plants and urban storm runoff. The system envisions that the data normally used during comprehensive planning studies would be encoded and processed onto a computer storage device (such as tape or disc) by application of the various Data Bank Management programs. The specifio pro- grams used would depend on the form in which the digitized data is received; either point, grid, contour or polygon, the form being dependent upon the nature of the variable and the relative advantages and disadvantages of alternative encoding methods. The initial input data are the basic resource maps that are encoded and placed into the data bank. Analysis would be performed for a selected development condition (alternative future, e.g., a projected land use pattern with a certain flood hazard zoning policy) by processing the development into the data bank as a new variable and successively executing the Interface and Comprehensive Analysis programs. The specific executions that are per- formed would be dependent upon the specific nature of the alternative future that is assessed. The comprehensive assessments require specific input data such as the hydrologic structure of the area, stream geometry, t.:alibrated storms, relationships between land use and runoff, damage potential, storm pollutant washoff. etc. The initial modeling cali. bration data is prepared conventionally based on observed data supplemented by paramo eters generated from the data bank and then the calibration data is used as the mechanism for forecasting the change in modeling data that would be caused by development alter. natives. The system output indudes I) grid map graphic displays of the data variables, attrac. tiveness, and impact analysis results; and 2) detailed numeric printout of runoff hydro. graphs, flow exceedance frequency relationships, expected annual damages, storm pollu- tographs and time traces of erosion and a range of water quality parameters for existing and the selected alternative future development patterns. The output corresponds to the complete range of technical output of comprehensive flood plain assessments. , . . : e 5 L..